Today is the anniversary of Dmitri Mandeleev’s birthday, the father of the periodic table. After previous attempts to put the periodic table of the elements into a meaningful order by relative atomic mass failed, Mandeleev finally succeeded by ordering the elements by atomic number, the number of positively charged protons in the nucleus of atoms of each element. This turned out to be the critical distinguishing feature of each element and the periodic table thus produced organised the elements into rows and columns of chemically related elements that share common properties. This allowed the properties and positions in the periodic table of undiscovered elements to be predicted.
Photo by CalamityJon